Question: Khan.scratchpad.disable(); To move up to the maestro level in his piano school, Ben needs to master at least $128$ songs. Ben has already mastered $42$ songs. If Ben can master $10$ songs per month, what is the minimum number of months it will take him to move to the maestro level?
To solve this, let's set up an expression to show how many songs Ben will have mastered after each month. Number of songs mastered $=$ $ $ Months at school $\times$ Songs mastered per month $+$ Songs already mastered Since Ben Needs to have at least $128$ songs mastered to move to maestro level, we can set up an inequality to find the number of months needed. Number of songs mastered $\geq 128$ Months at school $\times$ Songs mastered per month $ +$ Songs already mastered $\geq 128$ We are solving for the months spent at school, so let the number of months be represented by the variable $x$ We can now plug in: $x \cdot 10 + 42 \geq 128$ $ x \cdot 10 \geq 128 - 42 $ $ x \cdot 10 \geq 86 $ $x \geq \dfrac{86}{10} \approx 8.60$ Since we only care about whole months that Ben has spent working, we round $8.60$ up to $9$ Ben must work for at least 9 months.